Types of Social Networking Websites
There are dozens of social networking websites available online, each with its own special something to offer its members. From knitting-enthusiasts to patriotic Norwegians, and everyone in between...
Broad-range social networking websites
Some social networking websites, such as Facebook, fall in the "general" category; they accommodate folks of all interests and backgrounds. On this type of social networking websites, members can often include a list of their interests...

... and then locate members with similar interests by searching for keywords and keyphrases.

The main purpose of general social networking websites is to serve as a social platform where people can reunite with old friends, stay connected with current ones, and even make new acquaintances.
Niche social networking websites
Other social networking websites have tight, niche focuses, and cater to specific groups of people. Social networking websites can revolve around sports, dating, culture, hobbies, ethnicity, education, romance, entrepreneurship and more.
For example, this social networking websites is geared towards film - members can gather on Flixster to discuss, debate, rate and review movies on a social platform:

Wikipedia.org has a comprehensive list of social networking websites, from all-purpose to the obscure - I highly recommend you check it out!
Now that you know about the different types of social networking websites, find out how social networking can help your company.